The present invention relates to processing of electronic money using a dedicated media such as an IC card or a smart card, and in particular, to an electronic money processing method and an electronic money storage apparatus which makes it possible to automatically collect, in a remittance or transfer of money from a remitter to a remittee or a receiver, a commission or a transaction fee without any third person other than the remitter and the receiver.
Heretofore, there has been actually implemented the processing of electronic money using a dedicated media such as an IC card, for example, a balance managing type described in JP-A-5-504643 and a token type described in JP-A-9-128465.
First, description will be given of the electronic money of the balance managing type of JP-A-5-504643.
The remitter is assigned with an electronic money storage apparatus which keeps a shared public key Kpg, a private key Ks1 unique to the electronic money storage apparatus, and an encrypted code Kp1*Ksg obtained by encrypting a public key Kp1 unique to the storage apparatus in accordance with a shared private key Ksg.
Similarly, the remittee is assigned with an electronic money storage apparatus which keeps a shared public key Kpg, a private key Ks2 unique to the electronic money storage apparatus, and an encrypted code Kp2*Ksg obtained by encrypting a public key Kp2 unique to the storage apparatus in accordance with the shared private key Ksg. In addition, an amount of electronic money is stored as amount information (numeric value) in each electronic storage apparatus.
Electronic money is moved or transferred between the electronic money storage apparatuses as follows.
The electronic money storage apparatus of the remitter transmits Kp1*Ksg, storage information encrypted by Ks1, and the like to the electronic money storage apparatus of the receiver.
The electronic money storage apparatus of the receiver defrosts or decomposes the received Kp1*Ksg by the shared public key Kpg to resultantly attain the public key Kp1 unique to the remitter's electronic money storage apparatus. Using the public key Kp1, the electronic money storage apparatus of the receiver obtains information such as storage information of the remitter's electronic money storage apparatus to thereby authenticate the remitter's electronic money storage apparatus.
Similarly, the remitter's electronic money storage apparatus authenticates the receiver's electronic money storage apparatus. Both electronic money storage apparatuses mutually authenticate each other in this way to share the respective public keys therebetween.
Thereafter, the remitter's electronic money storage apparatus subtracts an amount of remittance from an amount in an electronic money storage and then notifies an encrypted message of the reduction to the receiver's electronic money storage apparatus. On receiving the notification, the receivers storage apparatus adds the amount of remittance to its balance to thereby receive electronic money.
Subsequently, description will be given of electronic money of the token type.
For the token-type electronic money, data with an electronic signature of an electronic money issuer is treated as data representing a value.
Electronic money is issued in the following procedure.
A person who desires to issue electronic money sends a kind of random numbers obtained by conducting a type of transform on original random numbers, an amount to be issued, account information, and the like to an electronic money issuer.
The electronic money issuer confirms the amount requested and account information, writes its signature representing the requested amount for the received data of random numbers, and then returns the resultant data to the electronic money requester.
The electronic money requester conducts a certain kind of transform on the received data and then stores the data thus transformed in an electronic money storage. The stored data is called "token". As an example of the sequence of transform procedure, there exists "blind signature".
When electronic money is to be used, a token is moved from a remitter's electronic money storage apparatus to a receiver's electronic money storage apparatus. A method of subdivision of value and a method of checking duplicated usage have been described in detailed in the Article above and hence will not be described in this application.
The processing above can be summarized as shown in FIG. 3, which will be next described.
First, a remitter's electronic money storage apparatus 1100 and a receiver's electronic money storage apparatus 1200 communicate via a data transfer apparatus, not shown, information of respective storage apparatuses and a remittance amount therebetween (steps 3101 and 3201).
Next, the remittance amount p is attained from an electronic money storage area 1131 (step 3103).
Thereafter, the remitter's storage apparatus 1100 remits electronic money of an amount of p via a data transfer unit to the receiver's storage apparatus 1200 (step 3106).
The receiver's storage apparatus 1200 then receives the electronic money (step 3203) and then stores the amount of money p in an electronic money storage area 1231 (step 3205).
As the electronic money storage apparatus, there can be considered, for example, an IC card having an arithmetic processing function. As the data transfer unit, there exist, for example, a portable electronic money processing apparatus called "electronic wallet" and two computers connected to an IC card reader-writer via a communication line such as the Internet.
In addition to the electronic money of the IC card type, there exists, for example, electronic money of a network type described in pages 96 to 101 of "Scientific American", August 1992.
In the processing of the network-type electronic money, tokens are stored in a general storage such as a hard disk unit.
The processing ranging from the issuance of electronic money by an electronic money issuing institute or organization for the remitter to the transmission of the token from the remitter to the receiver, is the same as the token processing of the IC-card-type electronic money.
The receiver transmits the received token via a network to the electronic money issuing institute as a third person. The institute makes a check for validity of the token and presence or absence of an illegal use thereof.
However, in the processing of the conventional IC-card-type electronic money, the money remitting operation is carried out without any intervention of a third person and hence it is difficult for the electronic money issuer or the like to collect a transaction fee of electronic money.
Furthermore, in a processing system of, for example, the network-type electronic money in which an intervention of a third person takes place via a communication network or the like, it is always required to notify remittance information to a third person. Namely, this processing is possible only with a communication line, which disadvantageously leads to a problem of deterioration in usability of the processing system.
In the conventional methods described above, when the usability is emphasized for the persons related to remittance of money, the transaction fee cannot be collected; moreover, when the transaction fee is collected through communication, the usability is sacrificed.